The topic of the final work are X-ray devices in medicine. In the first part of the paper, Ionizing Radiation is described as it is generated and Ionizing radiation is detected. Then, the radiobiology and consequences of human exposure to ionizing radiation and legal regulation of ionizing radiation in the Republic of Croatia are explained. Afterwards, X-ray devices in medicine, operating principles of the device, basic parts of the device, device types, and facilities described, and at the end of the work, are covered by the X-ray radiation protection, protective devices and equipment and the supervision of exposed workers.